Technics RS-M228X - Page 9

RS-M228X
¢ ADJUSTMENT PARTS LOCATION OF dbx SYSTEM
VR204 VR206
(320
1
\ Lo
TP206
f eae
R2508 |;
/
a a
TP204
240
NS
» ae
\
ee
id
., TP207 ~
Tbreos
\
cs
\
press
‘
{press
VR203 VR205
TP205 >,
a apl \
* Pyreas
X nae
cen
7 TP203 ~TP201
Fig. 2
BLOCK DIAGRAM OF dbx
SECTION (L-CH ONLY)
{@P) NIVOWOA
20 wo 500 th Sr 10k 2OKM:
[PRE EMPAHSIS CHARACTARISTIC]
20 100 «500 tk Bh 10k 2OmHe
B00 O
{DE- EMPHASIS CHARACTARISTIC}
100
CONTROL VOLTAGE (mV)
[VCA CHARACTARISTIC]
300 SOO tk Se 10n 20Kne
(BAND PASS FILTER CHARACTARISTIC]
DISe. MODE (DECODE: S1; disc position)
dbx CIRCUIT BOARD
VR201
VCA Symmetry
adjustment VR
Q203
INPUT BAND
PASS FILTER
(27 Hz—20 kHz]
VCA
1€201, 205
L-CH
output
DE EMPHASIS
VR203
RMS detector
adjustment VR
1203
RMS
DETECTOR
VR207
dbx standard level
adjustment VR (Decode)
1C205 Q221
RMS FILTER
(27 Hz—10 kHz)
Q201, 207, 209, 217, 219
205, 213, 215, 211
CONTROL CIRCUIT
Q13, 14, 15, 16
CONTROL CIRCUIT From. St
(NR select switch)
bey
test
‘Tt
HI
2 00 «S00 hk ‘Bk 10K 2OKH2
[RMS WEIGHTING CHARACTARISTIC]
bie
ne mi
=50—40- 30-20-10 0+10+ 20430440450
RMS DETECTOR INPUT LEVEL (dB)
[RMS DETECTOR CHARACTARISTIC]
L 1
20 00 500 tk Ge Ok 2OKHz
IRMS FILTER CHARACTARISTIC]
Note: Encode/decode selection of the dbx circuit in RS-M228X
is done with a control circuit, composed of transistors.
(This control circuit is interlocked with S2 (NR selection
switch).) 13
T T T q T 7 qT [ENCODE OUTPUT CHARACTARISTIC]
te ate
est ttHttte st + Set f
st oetit+ 4444 a a
t +4 CONTROL VOLTAGE (mv)
of itt Hatt |
93 iat Hi (VCA CHARACTARISTIC]
atte + +e
“Trt
3s 10s 20KH2 Cit Lum
20 wo $00 Sex 10k 2OKHE
{BAND PASS FILTER CHARACTARISTIC]
ENCODE MODE\ (RECORD MODE: S1: dbx tape position)
VCA Symmetry
adjustment VR
PRE
EMPHASIS
VR203
RMS detector
adjustment VR
Q203
LOW CUT
FILTER
VR205
dbx standard level
adjustment VR
O1P205|
TP207
1C203
RMS DETECTOR
RMS
WEIGHTING
1C205, Q221
RMS FILTER
Q201, 207, 209, 217
219, 213, 215, 211
CONTROL CIRCUIT
Q13, 14, 15, 16
CONTROL CIRCUIT
From S1
(NR select switch)
+300}
+240]
+180
+120
+60
~60
-120
—180
~ 240
300} -
=50=-40-30-20-1O HO+430440+50
AMS DETECCAR input tevel (dB)
{RMS DETECTORG HARACTARISTIC]
20 7007 BOQ Sm TOK Oks
[RMS WEIGHTING CHARACTARISTIC}
i i
Sk 1k 2OW2
{RMS BAND PASS FILTER CHARACTARISTICI
Fig. 3